Every competent person has a legal right to make decisions about one's own medical care. This includes deciding whether to accept or refuse care. Unfortunately, illness may make it difficult or impossible to exercise that legal right. A person can become temporarily or permanently legally incompetent to make decisions.

A person in this circumstance does not lose the right to make a decision; rather, one loses the legal ability to carry out personal wishes due to their legal incapacity to make decisions that reflect those wishes.

To make matters more difficult, should you become legally incompetent, health care providers do not need to abide by your decisions if they conflict with the health-care providers' professional judgment.

The way to enforce your wishes about future medical-care decisions is to make them in advance and place them in a legally enforceable "advance directive" document. Then, health care providers can be directed by your wishes, whether they agree with them or not.

What is an advance directive? It is a document in which a competent person states medical decisions for the future. Advance directive requirements vary greatly from state to state, and I would advise you to consult an attorney when creating your plan. Before you begin, you should understand that there are two types of advance directives available to you: (1) a living will containing written directives to health care providers and (2) a health care proxy or "power-of-attorney for health-care decision making," in which you designate a person who will be sympathetic to your desires in medical decision making to act as your agent if you are incapacitated.

Many standard legal forms for advance directives contain only one of these two types. I advise people to have both.

Why have both? A living will establishes certain treatment guidelines that are to be followed in the future. A health care proxy doesn't establish guidelines directly. Instead, it appoints a trusted person to make decisions for you if you cannot make them for yourself.

Because it is almost impossible to predict all the circumstances that might arise during a future illness, it is difficult to create a complete living will. The health care proxy preserves your right to self-determination.

But my family knows my wishes. If you become incapacitated and you don't have specific advance directives, your family members will generally be deemed the appropriate decision makers. Most courts agree that family members are the appropriate decision makers.

But, decisions made by family members who do not have an enforceable health care proxy are not followed by health care providers if the providers either question the good faith of the family member or strongly disagree with the medical decision.

If, however, the family member has been made your health care proxy, health care providers must treat those decisions as if you made them yourself. They will not be able to deviate from them just because they may happen to disagree. Thus, proxies are critical devices, especially for anyone whose values differ from those of the health care community.

A proxy is not a surrogate An important distinction must be made between a proxy and a surrogate. A proxy, designated by advance directive, was directly appointed by the now-incapacitated person. A surrogate is legally appointed by someone else. Surrogates may be empowered by appointment by a court, or by a legal relationship, such as marriage or kinship, that automatically gives the right to make decisions. But a surrogate may not be able to enforce decisions.

Examples of this often arise in quality-of-life decisions. Quality-of-life decisions by health care proxies are almost invariably followed. Quality-of-life decisions made by surrogates are often closely scrutinized by others to make sure they conform to the incapacitated person's wishes or best interests, as interpreted by a health care professional.

Clearly, the best way to ensure that your personal wishes are not overridden is to draw up a complete set of legally enforceable advance directives, including both living will and health-care proxy documents.

The health-care proxy document can incorporate provisions of the living will, requiring the person you name to follow any directives stated in your living will. The living will document can also incorporate the health care proxy, in which case the authority of your proxy would be limited by any conditions you have spelled out in your living will. But whether you have one legal document or two, be sure you have both living will and health-care proxy protections.